a rule stating that you may date/hook up with one person a year who is a 4 or lower on the attractiveness scale and noone can make fun of you to your face, if and only if you claim that person as your mulligan

repeat offenses are allowed with the same person with only slight taunting after

A Mulligan, in a game, happens when a player gets a second chance to perform a certain move or action; usually due to lack of skill or bitter luck. A "Do-Over". Like getting an "Extra Play" in pinball due to sinking the ball before obtaining an arbitrary amount of points.

If your opening hand in Magic: The Gathering sucks bad; just call "Mulligan", reshuffle, and draw new cards.

The Urban Dictionary T-Shirt

When a dating relationship is brutally derailed by submerged emotional issues unknown to either person. If the derailer is allowed a second chance by the derailed, its a Mulligan. Even more so it accompanied by a decent bitch slap.

Wes: Dude, I can't believe all this time I didn't realize I was a sad bastard with ungodly sorrow, projecting my emotional issues on you! Please bitch slap my issues back into my subconscious and give me a Mulligan.

Laura: Fine. Take me to a nice restaurant on Friday night and it'll be fine...SMACK!

The Urban Dictionary T-Shirt

When a man goes to bed with a woman with the intention of having sex, but is too drunk to perform either to a decent standard or at all. If the woman allows the man another attempt in the morning to redeem himself, this is known as a mulligan.

Man I ended up sleeping with Jessica last night, but i was so trashed i just couldn't do it! It's ok though, all was not lost, I grabbed the mulligan